Cation transport is to be evaluated in normal versus transformed cultured mammalian cells at different growth stages and during the cell cycle. Cellular cyclic AMP levels under these conditions will also be evaluated. Experiments are designed to assess the interrelationships between cAMP and cation transport in the normal and transformed cells. The role of cAMP in the regulation of cation transport or, in turn, the role of cation transport in the regulation of intracellular cAMP will be evaluated to determine the regulatory function of these phenomena in relation to control of the cell cycle. Manipulation of membrane transport and cellular cAMP are envisioned to assess the potential ability of these factors to exert density-dependent growth inhibition in normal cells and to determine their involvement in the absence of such growth control in malignant cells. BIBLIOGRAPHIC REFERENCES: Tupper, J. T., Mills, B. and Zorgniotti, F. 1976 Transport in Synchronized Ehrlich Ascites Tumor Cells: Amino Acid Transport by the A and L Systems. J. Cell. Physiol., in press. Mills, B. and Tupper, J. T. 1976 Cell Cycle Dependent Changes in Potassium Transport. J. Cell. Physiol., in press.